Musar su Salmi 127:1

The general rule is that they must conduct themselves with modesty and confine their relations to the time that is designated for this, that is, after midnight when all the members of the household are asleep. And let them be careful not to have relations in the presence of any living creature. Thus the Gemara relates that Abaye used to chase away the mosquitoes and Rova used to chase away the flies. In Zohar Chadash (15a) it is taught in the name of Rav Huna: “A person must sanctify himself to the name of Heaven at the time of relations, as it is written, ‘If Hashem does not build a house, its builders have toiled in vain’ (Tehillim 127a).” The idea is this: If their intentions are not for the sake of Heaven, to produce God-fearing and scholarly children, but for the sake of their own pleasure, then their toil is “in vain” because their intentions are for pure vanity. That is, to satisfy the evil inclination and fulfill their alien thoughts of pleasure.

In the case of David we find the reverse process. David, who always tried to involve G–d in all that goes on here on earth, tried to build a sanctuary to provide G–d with a permanent abode here on earth, and thereby to reverse any separation between man and G–d. This is the deeper significance of the מגדל דוד … בנוי לתלפיות, "the tower of David built as an ornament" (Song of Songs 4,4). The Temple was the structure that all mankind is meant to turn to as a symbol of G–d's Presence on earth. Despite David's intentions and endeavors, G–d's ultimate Sanctuary has not yet been built on earth; a structure built by humans would not endure. This is what the Psalmist means when he says אם ה' לא יבנה בית שוא עמלו בוניו בו, "if G–d Himself does not build the house, its builders labor in vain with it" (Psalms 127,1).

The sounding of the Shofar is reminiscent of an ancient custom in Israel that when someone died, the sounding of the Shofar was a signal for people to attend the burial (Moed Katan 27). The seventieth year, which symbolizes the end of a normal lifespan, is to remind one of impending death and the accounting one has to render. The blowing of the Shofar is also in order on the Day of Atonement (25,9) when one renews one's life after having secured forgiveness. When verse 10 speaks about "return to one's original possession," the meaning includes return to one's former innocence. Death secures the atonement for those who return to G–d, i.e. when the spirit returns to G–d, as Solomon said in Kohelet 12,7. These are all thoughts that man should constantly bear in mind, they should not be קרי, something he thinks about only incidentally. One needs to think of oneself as an alien, גר, in this world, not as a permanent fixture. This is what the Torah implies in 25,23: כי גרים ותושבים אתם עמדי, "For you are strangers and residents with Me." We will not acquire permanency until we arrive in the Hereafter. The last verse seems self-contradictory. Either we are strangers or we are residents. How can we be both? The answer is that as long as we do not sanctify ourselves as the Torah wishes us to do, our tenure is no more than that of strangers, גרים; once we have sanctified ourselves through our Torah-oriented lifestyles, however, we acquire tenure, i.e. become תושבים. The warning not to view ourselves as possessing tenure on earth is expressed more forcefully by the legislation that land cannot be sold permanently (25,23). People who live under the illusion that land ownership secures them tenure on this earth are fools. They forget what David reminded us of in Psalms 127,1 when he said: אם ה' לא יבנה בית שוא עמלו בוניו בו, "Unless the Lord builds the house its builders labor on it in vain." We have now explained how all these various paragraphs in our portion are linked together logically.